This application is based upon and claims the benefit of priority from the prior Japanese Patent Application No. 2000-091213, filed Mar. 29, 2000, the entire contents of which are incorporated herein by reference.
The present invention relates to a silver halide photographic lightsensitive material improved with respect to a ratio of photographic speed/radiation fog.
In recent years, the demands for photographic lightsensitive materials, especially lightsensitive materials for photographing, are becoming stricter. It is now demanded to attain not only a high photographic speed but also a further reduction of radiation fog. Thus, it is desired to develop an emulsion improved with respect to them.
The techniques for enhancing the photographic speed of silver halide emulsions include one wherein tabular silver halide grains (hereinafter simply referred to as xe2x80x9ctabular grainsxe2x80x9d) are incorporated in silver halide emulsions. With respect to tabular grains, for example, U.S. Pat. Nos. 4,434,226, 4,439,520, 4,414,310, 4,433,048, 4,414,306 and 4,459,353, Jpn. Pat. Appln. KOKAI Publication No. (herein after referred to as JP-A-) 59-99433 and JP-A-62-209445 disclose processes for producing the same and techniques for use thereof. It is known that the tabular grains are advantageous in attaining, for example, an enhancement of photographic speed including enhancement of color sensitization efficiency by sensitizing dyes, an enhancement of photographic speed/graininess relations, an enhancement of sharpness attributed to specific optical properties of tabular grains, and an enhancement of covering power. Generally, in enhancing the photographic speed of silver halide emulsions, it is effective to employ tabular grains of large size and high aspect ratio.
On the other hand, it has been found that, the greater the enhancement of photographic speed, the more serious the problem of photographic performance deterioration by prolonged storage. The problem is especially serious with respect to color negative photographic lightsensitive materials with a photographic speed of ISO 400 or more. The causes of the photographic performance deterioration by prolonged storage involve not only hitherto well-known heat and moisture but also natural radiation (environmental radiation or cosmic rays). The lightsensitive material having been exposed to natural radiation suffers from an increase of fog density and, accompanying the same, a deterioration of graininess. As countermeasures to the deterioration of photographic performance by natural radiation, there are known, for example, the method of reducing the coating amount of silver (JP-A-63-226650 and JP-A-63-226651) and the method of reducing the potassium content of photographic lightsensitive materials (JP-A-2-836). Further, as measures for reducing the radiation fog, there are known the method of adding a mercaptoazole-type dye (JP-A-2-190851), the method of using a compound other than chloroauric acid as a gold sensitizer (JP-A-4-67032, JP-A-4-68337 and JP-A-4-75053), and the method of forming development initiation points on a single plane (for example, JP-A-5-216246). However, the tabular grains of large equivalent circle diameter and small grain thickness tend to suffer from radiation fog, and hence only the measures described in the above patent application specifications do not provide satisfactory countermeasures to the deterioration of photographic performance by natural radiation. Therefore, there is a demand for simultaneously attaining an enhancement of photographic speed and an enhancement of resistance to radiation with respect to these grains.
Moreover, in the above patent application specifications, there is no description relating to the speed at 3xc3x9710 9 sec exposure time being lower than the speed at 10xe2x88x925 sec exposure time by 30 or more in terms of speed unit, which is a feature of the emulsion which can be used in the silver halide photographic lightsensitive material of the present invention. The photographic performance at 10xe2x88x926 sec or less exposure time has not yet been studied partly because the exposure time is in the range not employed in practical photographing and partly because a special exposure device (laser) must be used under ultra-short duration exposure. Further, there is no literature referring to the interrelationship between photographic speed under ultra-short duration exposure and photographic speed under radiation.
It is an object of the present invention to improve the ratio of photographic speed/radiation fog of a silver halide photographic lightsensitive material. More specifically, it is an object of the present invention to provide a silver halide photographic lightsensitive material which realizes a reduction of radiation fog without any significant detriment to the practical photographic speed at usual exposure time ({fraction (1/100)} sec) and the practical reciprocity law (10xe2x88x925 to 10 sec exposure).
The inventor has made extensive and intensive studies. As a result, it has first been found that there is a correlation between the photographic speed under 10xe2x88x926 sec or less ultra-short duration exposure and the photographic speed under radiation with respect to tabular grains of large equivalent circle diameter and small grain thickness. Further, it has been found that a lightsensitive material improved with respect to the ratio of photographic speed/radiation fog can be obtained by carrying out, for example, not only reducing of the amount of gold used in after-ripening but also reducing of the amount of Ir in silver halide grains, increasing of the surface iodide content of silver halide grains, lowering of the (100) face proportion to grain side faces, etc. to thereby produce an emulsion exhibiting a large reciprocity low failure under ultra-short duration exposure without detriment to the photographic speed under {fraction (1/100)} sec exposure and the reciprocity law under 10xe2x88x925 to 10 sec exposure. Accordingly, the present invention provides the following silver halide photographic lightsensitive material.
(1) A silver halide photographic lightsensitive material comprising at least one lightsensitive silver halide emulsion layer on a support, wherein the lightsensitive material exhibits a speed at 3xc3x9710xe2x88x929 sec exposure time being lower than a speed at 10xe2x88x925 sec exposure time by 30 or more in terms of speed unit;
(2) The silver halide photographic lightsensitive material according to item (1) above, wherein the lightsensitive material exhibits a speed at 10xe2x88x925 sec exposure time being higher than a speed at 10 sec exposure time by 0 to 60 in terms of speed unit;
(3) The silver halide photographic lightsensitive material according to item (2) above, wherein the lightsensitive material exhibits a speed at 3xc3x9710xe2x88x929 sec exposure time being lower than a speed at 10xe2x88x925 sec exposure time by 50 or more in terms of speed unit;
(4) The silver halide photographic lightsensitive material according to any of items (1) to (3) above, wherein the at least one lightsensitive silver halide emulsion layer comprises an emulsion containing silver halide grains having a variation coefficient of equivalent circle diameter distribution of all the grains which is in a range of 40 to 3%, and 50% or more of the total projected area of all the silver halide grains is occupied by tabular grains of silver iodobromide or silver iodochlorobromide having (111) faces as main planes, the tabular grains having an equivalent circle diameter of 3.0 xcexcm or more and a thickness of 0.25 xcexcm or less;
(5) The silver halide photographic lightsensitive material according to item (4) above, wherein the variation coefficient of equivalent circle diameter distribution of the silver halide grains contained in the emulsion is in a range of 25 to 3%;
(6) The silver halide photographic lightsensitive material according to item (4) or (5) above, wherein 50% or more of the total projected area of all the silver halide grains contained in the emulsion is occupied by tabular grains having an equivalent circle diameter of 3.0 xcexcm or more and a thickness of 0.15 xcexcm or less;
(7) The silver halide photographic lightsensitive material according to item (4) or (5) above, wherein 50% or more of the total projected area of all the silver halide grains contained in the emulsion is occupied by tabular grains having an equivalent circle diameter of 4.0 xcexcm or more and a thickness of 0.15 xcexcm or less;
(8) The silver halide photographic lightsensitive material according to item (4) or (5) above, wherein 50% or more of the total projected area of all the silver halide grains contained in the emulsion is occupied by tabular grains having an equivalent circle diameter of 4.0 xcexcm or more and a thickness of 0.10 xcexcm or less; and
(9) The silver halide photographic lightsensitive material according to any of items (1) to (8) above, wherein the lightsensitive material has at least one blue-sensitive layer, at least one green-sensitive layer and at least one red-sensitive layer on the support, and exhibits a speed of ISO 400 or more.
The silver halide photographic lightsensitive material of the present invention will now be described. As one preferred embodiment of the lightsensitive material, there is provided a silver halide photographic lightsensitive material which exhibits a speed at 3xc3x9710xe2x88x929 sec exposure time being lower than a speed at 10xe2x88x925 sec exposure time by 30 or more in terms of speed unit.
The photographic characteristics will be described. The lightsensitive material of the present invention is characterized in that it exhibits a speed at 3xc3x9710xe2x88x929 sec exposure time being lower than a speed at 10xe2x88x925 sec exposure time by 30 or more, preferably 50 or more, in terms of speed unit. When the speed at 3xc3x9710xe2x88x929 sec exposure time is lower than the speed at 10xe2x88x925 sec exposure time by less than 30 in terms of speed unit, the radiation fog is extreme to an extent unfavorable in practical use. With respect to the lightsensitive material of the present invention, although the speed at 10xe2x88x925 sec exposure time is not limited, it is preferred that the speed at 10xe2x88x925 sec exposure time be higher than the speed at 10 sec exposure time by 0 to 60 in terms of speed unit, more preferably, by 0 to 40 in terms of speed unit. When the speed at 10xe2x88x925 sec exposure time is higher than the speed at 10 sec exposure time by over 60 in terms of speed unit, the reciprocity low failure is extreme to an extent unfavorable in practical use.
The silver halide photographic lightsensitive material of the invention preferably exhibits an ISO speed of 400 or more, and more preferably an ISO speed of 800 or more.
The speed unit will now be defined. First, the exposure system preferably employed in the determination of speed unit will be described. The exposure system can be varied depending on the exposure time. For example, tungsten sensitometer manufactured by Wakasa Kogaku Kenkyusho can be used when the exposure time is in the range of 10 to {fraction (1/100)} sec. For example, a sensitometer including xenon flash lamp manufactured by EG and G can be used when the exposure time is in the range of {fraction (1/100)} to 10xe2x88x925 sec. For example, a nanosecond pulse YAG laser can be used when the exposure time is 3xc3x9710xe2x88x929 sec. Visible light of variable wavelength can be emitted by the use of this YAG laser in combination with an optical parametric oscillator. The pulse width of the pulse laser is 3xc3x9710xe2x88x929 sec.
Now, the wavelength of irradiated light will be described. The wavelength of irradiated light is varied depending on whether the emulsion-containing layer is a blue-sensitive layer, or a green-sensitive layer, or a red-sensitive layer. In the case where light is irradiated to each of the blue-sensitive layer and the green-sensitive layer, preferable light has a wavelength distribution in which a peak thereof is within a range of xc2x110 nm from each of the wavelength giving a maximum absorption of the blue-sensitive layer and the green sensitive layer, respectively, and in which a half-value width thereof is 60 nm or less. In the case where light is irradiated to the red-sensitive layer, preferable light has a wavelength distribution in which a peak thereof is within a range of xc2x110 nm from the wavelength giving a maximum absorption of the red sensitive layer, and in which a range thereof spread xc2x150 nm from the maximum absorption. When a 10 to 10xe2x88x925 sec exposure is effected, light of preferred wavelength can be obtained by the use of, for example, a color filter. The blue-sensitive layer and the green-sensitive layer are irradiated with white lights of 5500 K color temperature having been passed through band-pass filters BPB-42 and BPB-53 manufactured by Fuji Photo Film Co., Ltd., respectively. The red-sensitive layer is irradiated with white light of 5500 K color temperature having been passed through sharp cut filter SC-62 and infrared cut filter both manufactured by Fuji Photo Film Co., Ltd. When a 3xc3x9710xe2x88x929 sec exposure is effected, monochromatic light of preferred wavelength can be obtained by regulating the oscillation wavelength by means of, for example, an optical parametric oscillator.
Now, the measuring of exposure quantity will be described. The exposure quantity of each of the above tungsten sensitometer, sensitometer using xenon flash lamp and nanosecond pulse YAG laser can be measured by the use of, for example, photometer manufactured by EG and G.
In the development, standard development (development time: 3 min 15 sec) is performed by means of color negative film development processing (CN-16 processing) manufactured by Fuji Photo Film Co., Ltd.
The density is determined by measuring an ISO status M diffusion transmission density. Under the above development conditions, the density exhibited when no exposure is made is referred to as the minimum density, and the greatest density exhibited when the exposure quantity is changed from 0 to infinity is referred to as the maximum density. The speed unit is defined by the formula:
(Speed unit)=100xc3x97(log10H) 
wherein H represents the exposure quantity required for realizing the density which is the middle of the minimum density and the maximum density.
The radiation fog mentioned in the present invention is an increase of the lowest density after development which is attributed to exposure of the sample to radiation. The radiation mentioned herein is mainly natural radiation, but may be artificially generated radiation. An intentional exposure to radiation can be accomplished by the use of, for example, 60Co xcex3-rays. The dose attained by exposure at a distance of 1 m from a radiation source to 37 GBq 60Co xcex3-rays for 8 min 10 sec is 0.2 R. The fog increment by radiation can be estimated from the difference between the fog density of the sample having been exposed to radiation and the fog density of the non-exposed sample.
The configuration of silver halide emulsion that can be used in the lightsensitive material of the present invention will be described below.
In the emulsion which can be used in the lightsensitive material of the present invention, 50% or more of the total projected area is occupied by tabular grains of silver iodobromide or silver iodochlorobromide having (111) faces as main planes. Herein, the expression xe2x80x9ctabular silver halide grainsxe2x80x9d is a general term for silver halide grains having one twin face or two or more mutually parallel twin faces. The twin face refers to the (111) face on both sides of which the ions of all the lattice points are in the relationship of reflected images. The tabular grains, as viewed from a point perpendicular to the main plane of the tabular grains, have the shape of a triangle, a hexagon or a circle as obtained by rounding thereof. The triangular, hexagonal and circular tabular grains have mutually parallel main planes which are triangular, hexagonal and circular, respectively.
The twin face spacing of the tabular grains which can be used in the lightsensitive material of the present invention may be 0.012 xcexcm or less as described in U.S. Pat. No. 5,219,720, the disclosure of which is incorporated herewith by reference or may be 15 or more in terms of (111) main plane spacing/twin face spacing as described in JP-A-5-249585, the disclosure of which is incorporated herewith by reference. The twin face spacing can be selected in conformity with the purpose of the use of the tabular grains.
With respect to the emulsion which can be used in the lightsensitive material of the present invention, the projected area of the above tabular grains preferably occupies 100 to 80%, more preferably 100 to 90%, and most preferably 100 to 95%, of the total projected area of all the grains. When the projected area of the tabular grains is less than 50% of the total projected area of all the grains, unfavorably, the advantages (enhancement of ratio of speed/graininess and sharpness) of the tabular grains cannot be fully utilized.
In the emulsion which can be used in the lightsensitive material of the present invention, it is preferred that hexagonal tabular grains whose neighboring side ratio (maximum side length/minimum side length) is in the range of 1.5 to 1 occupy 100 to 50% of the total projected area of all the grains of the emulsion. The above hexagonal tabular grains more preferably occupy 100 to 70%, most preferably 100 to 80%, of the total projected area. In the emulsion which can be used in the lightsensitive material of the present invention, it is especially preferred that hexagonal tabular grains whose neighboring side ratio (maximum side length/minimum side length) is in the range of 1.2 to 1 occupy 100 to 50% of the total projected area of all the grains of the emulsion. The above hexagonal tabular grains more preferably occupy 100 to 70%, most preferably 100 to 80%, of the total projected area. The mixing of tabular grains other than these hexagonal tabular grains into the emulsion is not favorable from the viewpoint of intergranular homogeneity.
In the emulsion which can be used in the lightsensitive material of the present invention, 50% or more of the total projected area of the emulsion is occupied by tabular grains having an equivalent circle diameter of 3.0 xcexcm or more and a thickness of 0.25 xcexcm or less, preferably tabular grains having an equivalent circle diameter of 3.0 xcexcm or more and a thickness of 0.15 xcexcm or less, more preferably tabular grains having an equivalent circle diameter of 4.0 xcexcm or more and a thickness of 0.15 xcexcm or less, and most preferably tabular grains having an equivalent circle diameter of 4.0 xcexcm or more and a thickness of 0.10 xcexcm or less. The emulsion is especially suitable when 80% or more of the total projected area of the emulsion is occupied by tabular grains having an equivalent circle diameter of 3.0 xcexcm or more and a thickness of 0.25 xcexcm or less, preferably tabular grains having an equivalent circle diameter of 3.0 xcexcm or more and a thickness of 0.15 xcexcm or less, more preferably tabular grains having an equivalent circle diameter of 4.0 xcexcm or more and a thickness of 0.15 xcexcm or less, and most preferably tabular grains having an equivalent circle diameter of 4.0 xcexcm or more and a thickness of 0.10 xcexcm or less. When the tabular grains fall outside these ranges, it is unfavorably difficult to realize the effects of the present invention.
In the present invention, the equivalent circle diameter refers to the diameter of a circle having the same area as the projected area of mutually parallel external surfaces of grains.
The projected area of grains can be determined by measuring the grain area on an electron micrograph and effecting a magnification correction thereto. The grain thickness can be easily determined by performing a vapor deposition of metal on grains, together with reference latex, in an oblique direction thereof, measuring the length of grain shadow on an electron micrograph and calculating with reference to the length of the latex shadow.
The average grain thickness of the tabular grains which can be used in the lightsensitive material of the present invention is preferably in the range of 0.03 to 0.25 xcexcm, more preferably 0.05 to 0.15 xcexcm, and most preferably 0.05 to 0.10 xcexcm. The average grain thickness is an arithmetic mean of the thicknesses of all tabular grains contained in the emulsion. It is difficult to prepare an emulsion wherein the average grain thickness is less than 0.03 xcexcm. On the other hand, when the average grain thickness exceeds 0.25 xcexcm, it is unfavorably difficult to realize the advantages of the tabular grains.
The average equivalent circle diameter of the tabular grains which can be used in the lightsensitive material of the present invention is preferably in the range of 3.0 to 6.0 xcexcm, more preferably 3.5 to 5.5 xcexcm, and most preferably 4.0 to 5.5 xcexcm. The average equivalent circle diameter is an arithmetic mean of the equivalent circle diameters of all tabular grains contained in the emulsion. When the average equivalent circle diameter falls outside these ranges, it is unfavorably difficult to realize the effects of the present invention.
The ratio of equivalent circle diameter to thickness with respect to silver halide grains is referred to as xe2x80x9caspect ratioxe2x80x9d. That is, the aspect ratio is the quotient of the equivalent circle diameter of the projected area of each individual silver halide grain divided by the grain thickness. One method of determining the aspect ratio comprises obtaining a transmission electron micrograph by the replica technique and measuring the diameter of a circle with the same area as the projected area of each individual grain (equivalent circle diameter) and the grain thickness. This grain thickness is calculated from the length of replica shadow.
It is preferred that the emulsion which can be used in the lightsensitive material of the present invention be composed of monodisperse grains. In the present invention, the variation coefficient of grain size (equivalent sphere diameter) distribution of all silver halide grains is preferably in the range of 35 to 3%, more preferably 25 to 3%, and most preferably 20 to 3%. The terminology xe2x80x9cvariation coefficient of equivalent sphere diameter distributionxe2x80x9d used herein means the product obtained by dividing the dispersion (standard deviation) of equivalent sphere diameters of individual tabular grains by the average equivalent sphere diameter and multiplying the resultant quotient by 100. That the variation coefficient of equivalent sphere diameter distribution of all tabular grains exceeds 35% is not favorable from the viewpoint of intergranular homogeneity. On the other hand, it is difficult to prepare an emulsion wherein the variation coefficient is below 3%.
The variation coefficient of equivalent circle diameter distribution of all grains contained in the emulsion which can be used in the lightsensitive material of the present invention is preferably in the range of 40 to 3%, more preferably 25 to 3%, and most preferably 20 to 3%. The terminology xe2x80x9cvariation coefficient of equivalent circle diameter distributionxe2x80x9d used herein means the product obtained by dividing the dispersion (standard deviation) of equivalent circle diameters of individual grains by the average equivalent circle diameter and multiplying the resultant quotient by 100. That the variation coefficient of equivalent circle diameter distribution of all grains exceeds 40% is not favorable from the viewpoint of intergranular homogeneity. On the other hand, it is difficult to prepare an emulsion wherein the variation coefficient is below 3%.
The variation coefficient of grain thickness distribution of all tabular grains contained in the emulsion which can be used in the lightsensitive material of the present invention is preferably in the range of 25 to 3%, more preferably 20 to 3%, and most preferably 15 to 3%. The terminology xe2x80x9cvariation coefficient of grain thickness distributionxe2x80x9d used herein means the product obtained by dividing the dispersion (standard deviation) of grain thicknesses of individual tabular grains by the average grain thickness and multiplying the resultant quotient by 100. That the variation coefficient of grain thickness distribution of all tabular grains exceeds 25% is not favorable from the viewpoint of intergranular homogeneity. On the other hand, it is difficult to prepare an emulsion wherein the variation coefficient is below 3%.
The variation coefficient of twin face spacing distribution of all tabular grains contained in the emulsion which can be used in the lightsensitive material of the present invention is preferably in the range of 25 to 3%, more preferably 20 to 3%, and most preferably 15 to 3%. The terminology xe2x80x9cvariation coefficient of twin face spacing distributionxe2x80x9d used herein means the product obtained by dividing the dispersion (standard deviation) of twin face spacings of individual tabular grains by the average twin face spacing and multiplying the resultant quotient by 100. That the variation coefficient of twin face spacing distribution of all tabular grains exceeds 25% is not favorable from the viewpoint of intergranular homogeneity. On the other hand, it is difficult to prepare an emulsion wherein the variation coefficient is below 3%.
In the present invention, although the grain thickness, aspect ratio and monodispersity can be selected within the above ranges in conformity with the purpose of the use thereof, it is desirable to employ monodisperse tabular grains of small grain thickness and high aspect ratio.
In the present invention, various methods can be employed for the formation of tabular grains of high aspect ratio. For example, the grain forming methods described in U.S. Pat. Nos. 5,496,694 and 5,498,516, the disclosures of which are incorporated herein by reference, can be employed. Further, the grain forming methods described in U.S. Pat. Nos. 5,494,789 and 5,503,970, the disclosures of which are incorporated herein by reference, can be employed for the formation of tabular grains of ultrahigh aspect ratio.
In the production of monodisperse tabular grains of high aspect ratio, it is important to form twinned crystal nuclei of small size within a short period of time. Thus, it is desirable to perform nucleation within a short period of time under low temperature, high pBr, low pH and small gelatin amount conditions. With respect to the type of gelatin, a gelatin of low molecular weight, a gelatin whose methionine content is low or a gelatin whose amino group is modified with, for example, phthalic acid, trimellitic acid or pyromellitic acid and the like are preferably employed.
After the nucleation, physical ripening is performed to thereby eliminate nuclei of regular crystals, single twinned crystals and nonparallel multiple twinned crystals while selectively causing nuclei of parallel double twinned crystals to remain. Further ripening among the remaining nuclei of parallel double twinned crystals is preferable from the viewpoint of enhancing the monodispersity.
Also, it is preferable to perform the physical ripening, for example, in the presence of PAO (polyalkylene oxide) as described in U.S. Pat. No. 5,147,771, the disclosure of which is incorporated herein by reference, from the viewpoint of enhancing the monodispersity.
Thereafter, supplemental gelatin is added, and soluble silver salts and soluble halides are added to thereby effect a grain growth. The above gelatin whose amino group is modified with, for example, phthalic acid, trimellitic acid or pyromellitic acid is preferably employed as the supplemental gelatin.
Further, the grain growth can preferably be performed by adding silver halide fine grains separately prepared in advance or simultaneously prepared in a separate reaction vessel to thereby feed silver and halide.
During the grain growth as well, it is important to control and optimize the temperature of reaction mixture, pH, amount of binder, pBr, feed speed of silver and halide ion, etc.
In the formation of silver halide emulsion grains for use in the present invention, it is preferable to employ silver iodobromide or silver chloroiodobromide. When there is a phase containing an iodide or a chloride, the phase may be uniformly distributed in each grain, or may be localized therein.
Furthermore, other silver salts, such as silver rhodanate, silver sulfide, silver selenide, silver carbonate, silver phosphate and an organic acid salt of silver, may be contained in the form of other separate grains or as parts of silver halide grains.
In the emulsion grains for use in the present invention, the silver bromide content is preferably 80 mol % or more, more preferably 90 mol % or more.
The silver iodide content of the emulsion grains for use in the present invention is preferably in the range of 1 to 20 mol %, more preferably 2 to 15 mol %, and most preferably 3 to 10 mol %. Silver iodide contents of less than 1 mol % are not suitable because it becomes difficult to realize the effects of increasing of dye adsorption, enhancing of intrinsic photographic speed, etc. On the other hand, silver iodide contents of more than 20 mol % are not suitable because the development velocity is generally delayed.
The variation coefficient of intergranular silver iodide content distribution in the emulsion grains for use in the present invention is preferably 30% or less, more preferably 25 to 3%, and most preferably 20 to 3%. That the variation coefficient exceeds 30% is not favorable from the viewpoint of intergranular homogeneity. The terminology xe2x80x9cvariation coefficient of intergranular silver iodide content distributionxe2x80x9d used herein means the product obtained by dividing the standard deviation of silver iodide contents of individual emulsion grains by the average silver iodide content and multiplying the resultant quotient by 100. The silver iodide contents of individual emulsion grains can be measured by analyzing the composition of each individual grain by means of an X-ray microanalyzer.
The measuring method is described in, for example, EP No. 147,868. In the determination of the distribution of silver iodide contents of individual grains contained in the emulsion which can be used in the lightsensitive material of the present invention, the silver iodide contents are preferably measured with respect to at least 100 grains, more preferably at least 200 grains, and most preferably at least 300 grains.
The tabular grains which can be used in the lightsensitive material of the present invention preferably have dislocation lines in the internal part thereof. The methods described in, for example, JP-A""s 63-220238, 1-201649 and 6-258745, the disclosures of which are incorporated herein by reference, can preferably be employed in the introduction of dislocation lines in the tabular grains.
The emulsion with the above configuration which can preferably be employed in the lightsensitive material of the present invention that exhibits a speed at 3xc3x9710xe2x88x929 sec exposure time being lower than a speed at 10xe2x88x925 sec exposure time by 30 or more in terms of speed unit will be described with reference to particular examples. In the present invention, the emulsion can preferably be prepared by, for example, (1) reducing the amount of iridium incorporated in silver halide grains, (2) increasing the surface iodide content, (3) reducing the ratio of (100) faces to grain side faces or (4) reducing the amount of gold added in after-ripening, to which, however, the methods available for the preparation of the emulsion are not limited. The emulsion which can preferably be employed in the lightsensitive material of the present invention, although can be disposed in any of the lightsensitive layers, is preferably disposed in a high-speed layer.
First, the incorporation of iridium in silver halide grains will be described. Water-soluble iridium salts and complex compounds can be mentioned as the iridium compounds which can be used in the present invention. In particular, examples of suitable iridium compounds include iridium trichloride, iridium tetrachloride and di- or penta-sodium, potassium or ammonium hexachloroiridate. With respect to the tabular grains for use in the present invention, it is preferred that the amount of iridium incorporated in the tabular grains be minimized as long as practical failure of the reciprocity law is not caused, from the viewpoint that the reciprocity low failure at ultra-short time exposure is increased. The amount of iridium incorporated in the tabular grains for use in the present invention, although variable depending on the silver halide composition of the tabular grains, the type of metal ion in polynuclear complex or cluster, the oxidation state of the metal ion and the type of ligand in the polynuclear complex or cluster, is preferably 10xe2x88x928 mol or less, more preferably in the range of 10xe2x88x9210 to 10xe2x88x928 mol, per mol of silver halide. When the amount of iridium is less than 10xe2x88x9210 mol per mol of silver halide, the reciprocity low failure at usual exposure time is unfavorably increased. On the other hand, when the amount of iridium exceeds 10xe2x88x928 mol per mol of silver halide, the reciprocity low failure at ultra-high illuminance is so small that it is unfavorably difficult to attain the effects of the present invention.
Regarding where to incorporate iridium, iridium can be added to an aqueous solution of gelatin as a dispersant, an aqueous solution of halide, an aqueous solution of silver salt or other aqueous solutions during the formation of silver halide grains. Alternatively, iridium is added in the form of silver halide fine grains containing a polynuclear complex or cluster in advance to the silver halide emulsion, and the incorporation in silver halide grains can be accomplished by, for example, dissolving the emulsion. Although the incorporation of iridium in silver halide grains can be performed at any of stages prior to grain formation, during grain formation and immediately after grain formation, it is preferred that the addition be effected during the grain formation.
In the silver halide grains which can be used in the lightsensitive material of the present invention, it is preferred that 50 mol % or more, especially 80 mol % or more, and most especially 100 mol %, of iridium be localized in the surface layer extending from the surface of each silver halide grain and constituting 50% or less of the grain volume. The volume of this surface layer is preferably 30% or less. The localization of iridium in the surface layer is effective in realizing a high speed while suppressing the increase of internal speed. The localized incorporation of a polynuclear complex or cluster in the surface layer of silver halide grains can be accomplished by, for example, first forming non-surface-layer portions of silver halide grains (core portions) and subsequently adding a solution of water-soluble silver salt and an aqueous solution of halide for forming the surface layer while simultaneously feeding iridium.
Preferred surface iodide content of the emulsion which can be used in the lightsensitive material of the present invention will now be described. From the viewpoint that the reciprocity low failure at ultra-high illuminance can be brought about, it is preferred that the surface iodide content of the emulsion which can be used in the lightsensitive material of the present invention be in the range of 3 to 8 mol %. The surface iodide content is more preferably in the range of 4 to 8 mol %, most preferably 5 to 8 mol %. When the surface iodide content is less than 3 mol %, it is unfavorably difficult to bring about the reciprocity low failure at ultra-high illuminance, thereby rendering exertion of the effects of the present invention difficult. On the other hand, when the surface iodide content exceeds 8 mol %, development inhibition or inhibition of chemical sensitization unfavorably occurs. The measuring of surface iodide content can be performed by the ESCA method (also known as the XPS method, which is the method in which X-rays are irradiated to grains and photoelectrons emitted from the grain surface are spectralized). Practical control of the surface iodide content can be accomplished by, for example, first forming silver halide base grains and subsequently adding a solution of water-soluble silver salt and an aqueous solution of halide for forming a surface shell while regulating the amount of potassium iodide in the aqueous solution of halide.
Below, the face indices of the surface of emulsion grains which can be used in the lightsensitive material of the present invention will be described. The surface of emulsion grains which can be used in the lightsensitive material of the present invention consists mainly of (111) and (100) faces. The ratio of (111) faces to the entire surface with respect to the emulsion grains which can be used in the lightsensitive material of the present invention is at least 70%.
With respect to the (100) faces, these appear on the sides of tabular grains in the emulsion grains which can be used in the lightsensitive material of the present invention. For control of the ratio of (100) faces, reference can be made to, for example, JP-A""s 2-298935 and 8-334850, the disclosures of which are incorporated herein by reference. The ratio of (100) faces to the entire surface area of grains can be determined by the method wherein the difference in adsorption dependency between (111) faces and (100) faces with respect to the adsorption of a sensitizing dye is utilized, for example, the method described in T. Tani, J. Imaging Sci., 29, 165 (1985).
The emulsion which can be used in the lightsensitive material of the present invention is occupied by tabular grains whose (100) face areal ratio to the side faces of emulsion grains is preferably in the range of 5 to 35%, more preferably 5 to 25%, and most preferably 5 to 20%. When the areal ratio falls outside these ranges, it is unfavorably difficult to attain the effects of the present invention. The (100) face areal ratio to the side faces of tabular grains can be determined by, for example, the method described in JP-A-8-334850, the disclosure of which is incorporated by reference.
That is, letting Cud be the ratio of the area which (111) faces occupy on the surface of an emulsion grain to the area which (100) faces occupy on the grain surface, an area ratio ECud of (100) faces in side faces of a tabular grain is
Cudxc3x97(ECD+2t)/2t 
where ECD: average equivalent circle diameter (xcexcm) t: average grain thickness (xcexcm) More specifically, the (100) face ratio is controlled by controlling the pAg, halogen composition, silver halide solvent concentration, and pH during the formation of silver halide grains, or by using a compound represented by formula (I) below:
YO(CH2CH2O)m(CH(CH3)CH2O)p(CH2CH2O)nYxe2x80x83xe2x80x83(I) 
In formula (I), Y represents a hydrogen atom, xe2x80x94SO3M, or xe2x80x94COBCOOM, M represents a hydrogen atom, an alkali metal atom, an ammonium group, or an alkyl-substituted ammonium group having 5 or less carbon atoms, B represents a chainlike or cyclic group for forming an organic dibasic acid, each of m and n represents an integer of 0 to 50, and p represents an integer of 1 to 100.
Practical examples of the compound represented by formula (I) are set forth below: 
In the present invention, the addition amount of the compound represented by formula (I) is 5xc3x9710xe2x88x922 g to 10 g per mole of silver halide.
It is preferable for the silver halide emulsion that can be used in the lightsensitive material of the invention to perform gold and chalcogen sensitizations. The chalcogen sensitization is performed with at least one of a sulfur sensitizer, a selenium sensitizer and a tellurium sensitizer.
The gold sensitization is usually performed by adding a gold sensitizer to the emulsion and stirring the emulsion for a predetermined time at a high temperature, preferably, 40xc2x0 C. or more.
As the gold sensitizers for the gold sensitization performed in the invention, the oxidation number of gold may be +1 or +3, and any gold compounds that are conventionally used as a gold sensitizer may be used. As representative examples of the gold sensitizer, chloroauric acid, potassium chloroaurate, aurictrichloride, potassium auricthiocyanate, potassiumu iodoaurate, tetracyanoauric acid, ammonium aurothiocyanate and pyridyltorichloro gold can be enumerated.
The addition amount of the fold sensitizer is preferably as low as possible as long as a practical sensitivity of the emulsion used in the invention is not greatly impaired, in view of lowering the sensitivity attained with an exposure of ultra-high illuminance. The addition amount of the gold sensitizer, although it may vary depending on the temperature at after-ripening, is preferably 1xc3x9710xe2x88x926 mol or less per mole of silver halide, more preferably, 1xc3x9710xe2x88x928 to 1xc3x9710xe2x88x926 mol per mole of silver halide. It is not preferable to increase the addition amount too large, because reciprocity law failure at ultra-high illuminance becomes too small.
The sulfur sensitization is usually performed by adding a sulfur sensitizer to the emulsion and stirring the emulsion for a predetermined time at a high temperature, preferably 40xc2x0 C. or more.
For the sulfur sensitization, compounds that are known as a sulfur sensitizer may be used. For example, thiosulfate, allylthiocarbamide urea, allylisothiocyanate, cystine, p-toluenethiosulfonic acid and rhodanine can be emumerated. In addition, the sulfur sensitizes described in the specifications of U.S. Pat. Nos. 1,547,944, 2,410,689, 2,278,947, 2,728,668, 3,501,313, and 3,656,955, and German Patent 1,422,868, and Jpn. Pat. Appln. KOKOKU Publication No. (hereinafter refereed to as JP-B) 56-24937, JP-A-55-45016 may be used. The addition amount of the sulfur sensitizer may be the one sufficient for effectively raise the sensitivity of the emulsion. The amount can be varied over a considerable range under various conditions such as pH, a temperature, and a size of a silver halide grain, but the amount is preferably, 1xc3x9710xe2x88x927 to 1xc3x9710xe2x88x924 mol per mole of silver halide.
The selenium sensitization can be performed by a conventionally known method. That is, the selenium sensitization is usually performed by adding labile selenium compounds and/or non-labile selenium compounds to the emulsion and stirring it for a predetermined time at a high temperature, preferably 40xc2x0 C. or more. The selenium sensitization using labile selenium compounds disclosed in JP-B-44-1578 is preferable performed. As specific selenium sensitizers, aliphatic isocyanates sucu as allyisoselenocyanate, selenoureas, selenoketones, selenoamides, selenocarboxylic acids and esters, and selenophosphates are emumerated.
Now, the tellulimu sensitization will be described. As tellulium sensitizers used in the invention, known tellulium sensitizers described in U.S. Pat. Nos. 1,623,499, 3,320,069, and 3,772,031, British Patent Nos. 235,211, 1,121,496, 1,295,462, and 1,396,696, and Canadian Patent No. 800,958, and JP-A-8-95184, and J. Chem. Soc. Chem. Commun. 635(1980), ibid 1102(1979), and ibid 645(1979), J. Chem. Soc. Perkin Trans. 1, 2191(1980), The chemistry of Organic Selenium and Telllurium compounds, Vol. 1(1986), S. Patai ed., and ibid Vol. 2(1987).
The followings are the description of the emulsions that are specified to be used in the lightsensitive material of the invention and other emulsions that can be used together.
Emulsions that are specified to be used in the lightsensitive material of the invention and other photographic emulsions that can be used together with the emulsions of the present invention can be prepared by the methods described in, e.g., P. Glafkides, Chimie et Physique Photographique, Paul Montel, 1967; G. F. Duffin, Photographic Emulsion Chemistry, Focal Press, 1966; and V. L. Zelikman et al., Making and Coating Photographic Emulsion, Focal Press, 1964. That is, any of an acid method, a neutral method, and an ammonia method can be used. In forming grains by the reaction of a soluble silver salt and a soluble halogen salt, any of the single-jet method, the double-jet method, and the combination of these methods can be used. It is also possible to use a method (so-called reverse double-jet method) of forming grains in the presence of excess silver ion. As one type of the double-jet method, a method in which the pAg of a liquid phase for producing a silver halide is maintained constant, i.e., a so-called controlled double-jet method can be used. This method makes it possible to obtain a silver halide emulsion in which the crystal shape is regular and the grain size is nearly uniform.
In some cases, it is preferable to make use of a method of adding silver halide grains already formed by precipitation to a reactor vessel for emulsion preparation, and the methods described in U.S. Pat. Nos. 4,334,012, 4,301,241, and 4,150,994, the discloses of which are herein incorporated by reference. These silver halide grains can be used as seed crystal and are also effective when supplied as a silver halide for growth. In the latter case, addition of an emulsion with a small grain size is preferable. The total amount of an emulsion can be added at one time, or an emulsion can be separately added a plurality of times or added continuously. In addition, it is sometimes effective to add grains having several different halogen compositions in order to modify the surface.
A method of converting most of or only a part of the halogen composition of a silver halide grain by a halogen conversion process is disclosed in, e.g., U.S. Pat. Nos. 3,477,852 and 4,142,900, European Patents (hereinafter also referred to as EU) 273,429 and 273,430, and West German Patent 3,819,241, the disclosers of which are incorporated herein by reference. This method is an effective grain formation method. To convert into a silver salt that is more sparingly soluble, it is possible to add a solution of a soluble halogen or silver halide grains. The conversion can be performed at one time, separately a plurality of times, or continuously.
As a grain growth method other than the method of adding a soluble silver salt and a halogen salt at a constant concentration and a constant flow rate, it is preferable to use a grain formation method in which the concentration or the flow rate is changed, such as described in British Patent (hereinafter also referred to as GB) 1,469,480 and U.S. Pat. Nos. 3,650,757 and 4,242,445, the disclosures of which are incorporated herein by reference. Increasing the concentration or the flow rate can change the amount of a silver halide to be supplied as a linear function, a quadratic function, or a more complex function of the addition time. It is also preferable to decrease the silver halide amount to be supplied if necessary depending on the situation. Furthermore, when a plurality of soluble silver salts of different solution compositions are to be added, a plurality of soluble halogen salts of different solution compositions are to be added or a method of increasing one of the salts while decreasing the other is also effective.
A mixing vessel for reacting solutions of soluble silver salts and soluble halogen salts can be selected from those described in U.S. Pat. Nos. 2,996,287, 3,342,605, 3,415,650, and 3,785,777 and West German Patents 2,556,885 and 2,555,364, the disclosures of which are incorporated herein by reference.
A silver halide solvent is useful for the purpose of accelerating ripening. As an example, it is known to make an excess of halogen ion exist in a reactor vessel in order to accelerate ripening. Another ripening agent can also be used. The total amount of these ripening agents can be mixed in a dispersing medium placed in a reactor vessel before addition of a silver salt and a halide salt or can be introduced to the reactor vessel simultaneously with addition of a halide salt, a silver salt, and a deflocculant. Alternatively, ripening agents can be independently added in the step of adding a halide salt and a silver salt.
Examples of the ripening agent are ammonia, thiocyanate (e.g., potassium rhodanate and ammonium rhodanate), an organic thioether compound (e.g., compounds described in U.S. Pat. Nos. 3,574,628, 3,021,215, 3,057,724, 3,038,805, 4,276,374, 4,297,439, 3,704,130, and 4,782,013 and JP-A-57-104926), a thione compound (e.g., four-substituted thioureas described in JP-A-53-82408, JP-A-55-77737, and U.S. Pat. No. 4,221,863, and compounds described in JP-A-53-144319), mercapto compounds capable of accelerating growth of silver halide grains, described in JP-A-57-202531, and an amine compound (e.g., JP-A-54-100717).
It is advantageous to use gelatin as a protective colloid for use in the preparation of emulsions of the present invention or as a binder for other hydrophilic colloid layers. However, another hydrophilic colloid can also be used in place of gelatin.
Examples of the hydrophilic colloid are protein such as a gelatin derivative, a graft polymer of gelatin and another high polymer, albumin, and casein; cellulose derivatives such as hydroxyethylcellulose, carboxymethylcellulose, and cellulose sulfates; sugar derivatives such as soda alginate and a starch derivative; and a variety of synthetic hydrophilic high polymers such as homopolymers or copolymers, e.g., polyvinyl alcohol, polyvinyl alcohol partial acetal, poly-N-vinylpyrrolidone, polyacrylic acid, polymethacrylic acid, polyacrylamide, polyvinylimidazole, and polyvinyl pyrazole.
Examples of gelatin are lime-processed gelatin, oxidated gelatin, and enzyme-processed gelatin described in Bull. Soc. Sci. Photo. Japan. No. 16, p. 30 (1966). In addition, a hydrolyzed product or an enzyme-decomposed product of gelatin can also be used.
It is preferable to wash with water an emulsion of the present invention to desalt, and disperse into a newly prepared protective colloid. Although the temperature of washing can be selected in accordance with the intended use, it is preferably 5xc2x0 C. to 50xc2x0 C. Although the pH of washing can also be selected in accordance with the intended use, it is preferably 2 to 10, and more preferably, 3 to 8. The pAg of washing is preferably 5 to 10, though it can also be selected in accordance with the intended use. The washing method can be selected from noodle washing, dialysis using a semipermeable membrane, centrifugal separation, coagulation precipitation, and ion exchange. The coagulation precipitation can be selected from a method using sulfate, a method using an organic solvent, a method using a water-soluble polymer, and a method using a gelatin derivative.
It is sometimes useful to perform a method of adding a chalcogen compound during preparation of an emulsion, such as described in U.S. Pat. No. 3,772,031. In addition to S, Se, and Te, cyanate, thiocyanate, selenocyanic acid, carbonate, phosphate, and acetate can be present.
In the formation of silver halide grains of the present invention, at least one of chalcogen sensitization including sulfur sensitization and selenium sensitization, and noble metal sensitization including gold sensitization and palladium sensitization, and reduction sensitization can be performed at any point during the process of manufacturing a silver halide emulsion. The use of two or more different sensitizing methods is preferable. Several different types of emulsions can be prepared by changing the timing at which the chemical sensitization is performed. The emulsion types are classified into: a type in which a chemical sensitization nucleus is embedded inside a grain, a type in which it is embedded in a shallow position from the surface of a grain, and a type in which it is formed on the surface of a grain. In emulsions of the present invention, the position of a chemical sensitization speck can be selected in accordance with the intended use. However, it is preferable to form at least one type of a chemical sensitization nucleus in the vicinity of the surface.
One chemical sensitization which can be preferably performed in the present invention is chalcogen sensitization, noble metal sensitization, or a combination of these. The sensitization can be performed by using active gelatin as described in T. H. James, The Theory of the Photographic Process, 4th ed., Macmillan, 1977, pages 67 to 76. The sensitization can also be performed by using any of sulfur, selenium, tellurium, gold, platinum, palladium, and iridium, or by using a combination of a plurality of these sensitizers at pAg 5 to 10, pH 5 to 8, and a temperature of 30xc2x0 C. to 80xc2x0 C., as described in Research Disclosure, Vol. 120, April, 1974, 12008, Research Disclosure, Vol. 34, June, 1975, 13452, U.S. Pat. Nos. 2,642,361, 3,297,446, 3,772,031, 3,857,711, 3,901,714, 4,266,018, and 3,904,415, and British Patent 1,315,755. In the noble metal sensitization, salts of noble metals, such as gold, platinum, palladium, and iridium, can be used. In particular, gold sensitization, palladium sensitization, or a combination of the both is preferred. In the gold sensitization, it is possible to use known compounds, such as chloroauric acid, potassium chloroaurate, potassium aurithiocyanate, gold sulfide, and gold selenide. A palladium compound means a divalent or tetravalent salt of palladium. A preferable palladium compound is represented by R2PdX6 or R2PdX4 wherein R represents a hydrogen atom, an alkali metal atom, or an ammonium group and X represents a halogen atom, e.g., a chlorine, bromine, or iodine atom.
More specifically, the palladium compound is preferably K2PdCl4, (NH4)2PdCl6, Na2PdCl4, (NH4)2PdCl4, Li2PdCl4, Na2PdCl6, or K2PdBr4. It is preferable that the gold compound and the palladium compound be used in combination with thiocyanate or selenocyanate.
Examples of a sulfur sensitizer are hypo, a thiourea-based compound, a rhodanine-based compound, and sulfur-containing compounds described in U.S. Pat. Nos. 3,857,711, 4,266,018, and 4,054,457. The chemical sensitization can also be performed in the presence of a so-called chemical sensitization aid. Examples of a useful chemical sensitization aid are compounds, such as azaindene, azapyridazine, and azapyrimidine, which are known as compounds capable of suppressing fog and increasing sensitivity in the process of chemical sensitization. Examples of the chemical sensitization aid and the modifier are described in U.S. Pat. Nos. 2,131,038, 3,411,914, and 3,554,757, JP-A-58-126526, and G. F. Duffin, Photographic Emulsion Chemistry, pages 138 to 143.
A preferable amount of a palladium compound is 1xc3x9710xe2x88x923 to 5xc3x9710xe2x88x927 mol per mol of a silver halide. A preferable amount of a thiocyan compound or a selenocyan compound is 5xc3x9710xe2x88x922 to 1xc3x9710xe2x88x926 mol per mol of a silver halide.
An amount of a sulfur sensitizer with respect to silver halide grains of the present invention is preferably 1xc3x9710xe2x88x924 to 1xc3x9710xe2x88x927 mol, and more preferably, 1xc3x9710xe2x88x925 to 5xc3x9710xe2x88x927 mol per mol of a silver halide.
Selenium sensitization is a preferable sensitizing method for emulsions of the present invention. Known labile selenium compounds are used in the selenium sensitization. Practical examples of the selenium compound are colloidal metal selenium, selenoureas (e.g., N,N-dimethylselenourea and N,N-diethylselenourea), selenoketones, and selenoamides. In some cases, it is preferable to perform the selenium sensitization in combination with one or both of the sulfur sensitization and the noble metal sensitization.
It is preferable to perform reduction sensitization during grain formation, after grain formation but before chemical sensitization, during chemical sensitization, or after chemical sensitization of the silver halide emulsion.
Reduction sensitization performed in the present invention can be selected from a method of adding reduction sensitizers to a silver halide emulsion, a method called silver ripening in which grains are grown or ripened in a low-pAg ambient at pAg 1 to 7, and a method called high-pH ripening in which grains are grown or ripened in a high-pH ambient at pH 8 to 11. It is also possible to combine two or more of these methods.
The method of adding reduction sensitizers is preferred in that the level of reduction sensitization can be finely adjusted.
Known examples of the reduction sensitizer are stannous chloride, ascorbic acid and its derivatives, amines and polyamines, hydrazine derivatives, formamidinesulfinic acid, a silane compound, and a borane compound. In reduction sensitization of the present invention, it is possible to selectively use these reduction sensitizers or to use two or more types of compounds together. Preferable compounds as the reduction sensitizer are stannous chloride, thiourea dioxide, dimethylamineborane, and ascorbic acid and its derivatives. Although the addition amount of reduction sensitizers must be so selected as to meet the emulsion manufacturing conditions, a proper amount is 10xe2x88x927 to 10xe2x88x922 mol per mol of a silver halide.
The reduction sensitizer is, for example, added during grain formation by dissolving thereof to water, or organic solvents such as alcohols, glycols, ketones, esters, and amides. The reduction sensitizer can previously added to a reaction vessel, but it is preferable to add the reduction sensitize at a proper timing during grain growth. It is also possible to previously add the reduction sensitizer to a solution of a water-soluble silver salt or of an alkaline halide, thereby to precipitate silver halide grains using the solutions. It is also preferable to add a solution of the reduction sensitizer at several times separately during the grain growth or add the solution for a consecutive long period.
It is preferable to use an oxidizer for silver during the process of manufacturing emulsions of the present invention. An oxidizer for silver means a compound having an effect of converting metal silver into silver ion. A particularly effective compound is the one that converts very fine silver grains, as a by-product in the process of formation of silver halide grains and chemical sensitization, into silver ion. The silver ion produced can form a silver salt hard to dissolve in water, such as a silver halide, silver sulfide, or silver selenide, or a silver salt easy to dissolve in water, such as silver nitrate. An oxidizer for silver can be either an inorganic or organic substance. Examples of the inorganic oxidizer are ozone, hydrogen peroxide and its adduct (e.g., NaBO2xc2x7H2O2xc2x73H2O, 2NaCO3xc2x73H2O2, Na4P2O7xc2x72H2O2, and 2Na2SO4xc2x7H2O2xc2x72H2O), peroxy acid salt (e.g., K2S2O8, K2C2O6, and K2P2O8), a peroxy complex compound (e.g., K2[Ti(O2)C2O4]xc2x73H2O, 4K2SO4xc2x7Ti(O2)OHxc2x7SO4xc2x72H2O, and Na3[VO(O2)(C2H4)2xe2x80x836H2O], permanganate (e.g., KMnO4), an oxyacid salt such as chromate (e.g., K2Cr2O7), a halogen element such as iodine and bromine, perhalogenate (e.g., potassium periodate), a salt of a high-valence metal (e.g., potassium hexacyanoferrate(II)), and thiosulfonate.
Examples of the organic oxidizer are quinones such as p-quinone, an organic peroxide such as peracetic acid and perbenzoic acid, and a compound for releasing active halogen (e.g., N-bromosuccinimide, chloramine T, and chloramine B).
Preferable oxidizers of the present invention are ozone, hydrogen peroxide and its adduct, a halogen element, an inorganic oxidizer of thiosulfonate, and an organic oxidizer of quinones. The combined use of the aforementioned reduction sensitizer and the oxidizer to silver is a preferable embodiment. The method of adding the oxidizer can be selected from the method of using the oxidizer followed by performing reduction sensitization, the vice versa thereof, or the method of making both of the oxidizer and the reduction sensitizer present at the same time. These methods can be performed at a grain formation step or a chemical sensitization step.
Photographic emulsions used in the present invention can contain various compounds in order to prevent fog during the manufacturing process, storage, or photographic processing of a sensitized material, or to stabilize photographic properties. Usable compounds are those known as an antifoggant or a stabilizer, for example, thiazoles, such as benzothiazolium salt, nitroimidazoles, nitrobenzimidazoles, chlorobenzimidazoles, bromobenzimidazoles, mercaptothiazoles, mercaptobenzothiazoles, mercaptobenzimidazoles, mercaptothiadiazoles, aminotriazoles, benzotriazoles, nitrobenzotriazoles, and mercaptotetrazoles (particularly 1-phenyl-5-mercaptotetrazole); mercaptopyrimidines; mercaptotriazines; a thioketo compound such as oxadolinethione; azaindenes, such as triazaindenes, tetrazaindenes (particularly hydroxy-substituted(1,3,3a,7)tetrazaindenes), and pentazaindenes. For example, compounds described in U.S. Pat. Nos. 3,954,474 and 3,982,947 and JP-B-52-28660 can be used. One preferable compound is described in JP-A-63-212932. Antifoggants and stabilizers can be added at any of several different timings, such as before, during, and after grain formation, during washing with water, during dispersion after the washing, before, during, and after chemical sensitization, and before coating, in accordance with the intended application. The antifoggants and the stabilizers can be added during preparation of an emulsion to achieve their original fog preventing effect and stabilizing effect. In addition, the antifoggants and the stabilizers can be used for various purposes of, e.g., controlling crystal habit of grains, decreasing a grain size, decreasing the solubility of grains, controlling chemical sensitization, and controlling an arrangement of dyes.
The photographic emulsion of the present invention is preferably subjected to a spectral sensitization with at least one methine dye or the like, from the viewpoint that the effects desired in the present invention can be exerted. Examples of usable dyes include cyanine dyes, merocyanine dyes, composite cyanine dyes, composite merocyanine dyes, holopolar cyanine dyes, hemicyanine dyes, styryl dyes and hemioxonol dyes. Particularly useful dyes are those belonging to cyanine dyes, merocyanine dyes and composite merocyanine dyes. Any of nuclei commonly used in cyanine dyes as basic heterocyclic nuclei can be applied to these dyes. Examples of such applicable nuclei include a pyrroline nucleus, an oxazoline nucleus, a thiozoline nucleus, a pyrrole nucleus, an oxazole nucleus, a thiazole nucleus, a selenazole nucleus, an imidazole nucleus, a tetrazole nucleus and a pyridine nucleus; nuclei comprising these nuclei fused with alicyclic hydrocarbon rings; and nuclei comprising these nuclei fused with aromatic hydrocarbon rings, such as an indolenine nucleus, a benzindolenine nucleus, an indole nucleus, a benzoxazole nucleus, a naphthoxazole nucleus, a benzothiazole nucleus, a naphthothiazole nucleus, a benzoselenazole nucleus, a benzimidazole nucleus and a quinoline nucleus. These nuclei may have at least one substituent on carbon atoms thereof.
Any of 5 or 6-membered heterocyclic nuclei such as a pyrazolin-5-one nucleus, a thiohydantoin nucleus, a 2-thioxazolidine-2,4-dione nucleus, a thiazolidine-2,4-dione nucleus, a rhodanine nucleus and a thiobarbituric acid nucleus can be applied as a nucleus having a ketomethylene structure to the merocyanine dye or composite merocyanine dye.
These spectral sensitizing dyes may be used either individually or in combination. The spectral sensitizing dyes are often used in combination for the purpose of attaining supersensitization. Representative examples thereof are described in U.S. Pat. Nos. 2,688,545, 2,977,229, 3,397,060, 3,522,052, 3,527,641, 3,617,293, 3,628,964, 3,666,480, 3,672,898, 3,679,428, 3,703,377, 3,769,301, 3,814,609, 3,837,862 and 4,026,707, and GB 1,344,281 and 1,507,803, JP-B""s-43-4936 and 53-12375 and JP-A""s-52-110618 and 52-109925.
The emulsion of the present invention may be doped with a dye which itself exerts no spectral sensitizing effect or a substance which absorbs substantially none of visible radiation and exhibits supersensitization, together with the above spectral sensitizing dye.
The emulsion may be doped with the spectral sensitizing dye at any stage of the process for preparing the emulsion which is known as being useful. Although the doping is most usually conducted at a stage between the completion of the chemical sensitization and before the coating, the spectral sensitizing dye can be added simultaneously with the chemical sensitizer to thereby simultaneously effect the spectral sensitization and the chemical sensitization as described in U.S. Pat. Nos. 3,628,969 and 4,225,666. Alternatively, the spectral sensitization can be conducted prior to the chemical sensitization as described in JP-A-58-113928, and also, the spectral sensitizing dye can be added prior to the completion of silver halide grain precipitation to thereby initiate the spectral sensitization. Further, the above compound can be divided prior to addition, that is, part of the compound can be added prior to the chemical sensitization with the rest of the compound added after the chemical sensitization as taught in U.S. Pat. No. 4,225,666. Still further, the spectral sensitizing dye can be added at any stage during the formation of silver halide grains, such as the method disclosed in U.S. Pat. No. 4,183,756 and other methods.
The addition amount of the spectral sensitizing dye can range from 4xc3x9710xe2x88x926 to 8xc3x9710xe2x88x923 mol per mol of the silver halide. In the case where a preferable silver halide grain size of 0.2 to 1.2 xcexcm, the addition amount of about 5xc3x9710xe2x88x925 to 2xc3x9710xe2x88x923 mol is effective.
In the lightsensitive material of the present invention, it is only required that at least one silver halide emulsion layer, preferably, at least three lightsensitive layers each provided with different ranges to each other, be formed on a support. A typical example is a silver halide photographic lightsensitive material having, on its support, at least one lightsensitive layer constituted by a plurality of silver halide emulsion layers which are sensitive to essentially the same color but have different sensitivities. This lightsensitive layer includes a unit lightsensitive layer which is sensitive to one of blue light, green light and red light. In a multilayered silver halide color photographic lightsensitive material, these unit lightsensitive layers are generally arranged in the order of red-, green- and blue-sensitive layers from a support. However, according to the intended use, this arrangement order may be reversed, or lightsensitive layers sensitive to the same color can sandwich another lightsensitive layer sensitive to a different color.
At least one non lightsensitive layer can be formed between the silver halide lightsensitive layers and as the uppermost layer and the lowermost layer. These intermediate layers may contain, e.g., couplers to be described later, DIR compounds and color-mixing inhibitors. As for a plurality of silver halide emulsion layers constituting respective unit lightsensitive layer, a two-layered structure of high- and low-speed emulsion layers can be preferably used in this order so as to the speed becomes lower toward the support as described in DE (German Patent) 1,121,470 or GB 923,045, the disclosures of which are incorporated herein by reference. Also, as described in JP-A""s-57-112751, 62-200350, 62-206541 and 62-206543, the disclosures of which are incorporated herein by reference, layers can be arranged such that a low-speed emulsion layer is formed farther from a support and a high-speed layer is formed closer to the support.
As described in JP-B-49-15495, the disclosure of which is incorporated herein by reference, three layers can be arranged such that a silver halide emulsion layer having the highest sensitivity is arranged as an upper layer, a silver halide emulsion layer having sensitivity lower than that of the upper layer is arranged as an interlayer, and a silver halide emulsion layer having sensitivity lower than that of the interlayer is arranged as a lower layer; i.e., three layers having different sensitivities can be arranged such that the sensitivity is sequentially decreased toward the support. Even when a layer structure is constituted by three layers having different sensitivities, these layers can be arranged in the order of medium-speed emulsion layer/high-speed emulsion layer/low-speed emulsion layer from the farthest side from a support in a layer sensitive to one color as described in JP-A-59-202464, the disclosure of which is incorporated herein by reference. In addition, the order of high-speed emulsion layer/low-speed emulsion layer/medium-speed emulsion layer or the order of low-speed emulsion layer/medium-speed emulsion layer/high-speed emulsion layer can be adopted. Furthermore, the arrangement can be changed as described above even when four or more layers are formed.
In addition, the lightsensitive material of the invention may have a emulsion layer having a fourth or more color sensitivities.
The layers of the fourth or more color sensitivities may be a layer that is sensitive to a wavelength region partially different from those of the blue-sensitive, green-sensitive, and red-sensitive layers. The fourth or more layers may be sensitive to infrared light or ultraviolet light. The coupler used therein can be selected depending on the purpose thereof.
When the lightsensitive material have unit layers each comprising three-layer structure, the layer structure of the lightsensitive material of the invention are enumerated as follows, however, the present invention is not limited to these. The order of the layer arrangement is from the layer nearer to the support.
1) low-speed red-sensitive emulsion layer (RLu), medium-speed red-sensitive emulsion layer (RLm), high-speed red-sensitive emulsion layer (RLo), low-speed green-sensitive emulsion layer (GLu), medium-speed green-sensitive emulsion layer (GLm), high-speed green-sensitive emulsion layer (GLo), low-speed blue-sensitive emulsion layer (BLu), medium-speed blue-sensitive emulsion layer (BLm), high-speed blue-sensitive emulsion layer (BLo);
2) GLu, GLm, GLo, RLu, RLm, RLo, BLu, BLm, BLo;
3) GLu, RLu, GLm, RLm, GLo, RLo, BLu, BLm, BLo;
4) GLu, GLm, RLu, RLm, GLo, RLo, BLu, BLm, BLo;
5) RLu, RLm, GLu, GLm, GLo, RLo, BLu, BLm, BLo;
6) GLu, RLu, RLm, GLm, GLo, RLo, BLu, BLm, BLo;
7) RLu, GLu, RLm, GLm, GLo, RLo, BLu, BLm, BLo;
8) GLu, GLm, RLm, GLm, RLo, GLo, BLu, BLm, BLo;
9) RLu, RLm, GLu, GLm, RLo, GLo, BLu, BLm, BLo;
10) GLu, GLm, RLu, RLm, RLo, GLo, BLu, BLm, BLo;
11) RLu, GLu, GLm, RLu, RLo, GLo, BLu, BLm, BLo;
12) GLu, RLu, GLm RLm, RLo, GLo, BLu, BLm, BLo.
Silver halide photographic lightsensitive material to which the present invention can be applied may contain various additives in accordance with its purposes.
These additives are described in detail in Research Disclosure Item 17643 (December 1978), Item 18716 (November 1979) and Item 308119 (December 1989), the disclosures of which are incorporated herein by reference. A summary of the locations where they are described will be listed in the following table.
With respect to the layer arrangement and related techniques, silver halide emulsions, dye forming couplers, DIR couplers and other functional couplers, various additives and development processing which can be used in the photographic lightsensitive material of the present invention and the emulsions suitable for use in the lightsensitive material, reference can be made to EP 0565096A1 (published on Oct. 13, 1993), the disclosure of which is incorporated herein by reference, and patents cited therein. Individual particulars and the locations where they are described will be listed below.
1. Layer arrangement: page 61 lines 23 to 35, page 61 line 41 to page 62 line 14,
2. Interlayers: page 61 lines 36 to 40,
3. Interlayer effect imparting layers: page 62 lines 15 to 18,
4. Silver halide halogen compositions: page 62 lines 21 to 25,
5. Silver halide grain crystal habits: page 62 lines 26 to 30,
6. Silver halide grain sizes: page 62 lines 31 to 34,
7. Emulsion production methods: page 62 lines 35 to 40,
8. Silver halide grain size distributions: page 62 lines 41 to 42,
9. Tabular grains: page 62 lines 43 to 46,
10. Internal structures of grains: page 62 lines 47 to 53,
11. Latent image forming types of emulsions: page 62 line 54 to page 63 to line 5,
12. Physical ripening and chemical sensitization of emulsion: page 63 lines 6 to 9,
13. Emulsion mixing: page 63 lines 10 to 13,
14. Fogging emulsions: page 63 lines 14 to 31,
15. Nonlightsensitive emulsions: page 63 lines 32 to 43,
16. Silver coating amounts: page 63 lines 49 to 50,
17. Photographic additives usable in the present invention are also described in RD, Item 17643 (December, 1978), Item 18716 (November, 1979) and Item 307105 (November, 1989) and the relevant description portions are summarized in the following table.
18. Formaldehyde scavengers: page 64 lines 54 to 57,
19. Mercapto antifoggants: page 65 lines 1 to 2,
20. Fogging agent, etc.-releasing agents: page 65 lines 3 to 7,
21. Dyes: page 65, lines 7 to 10,
22. Color coupler summary: page 65 lines 11 to 13,
23. Yellow, magenta and cyan couplers: page 65 lines 14 to 25,
24. Polymer couplers: page 65 lines 26 to 28,
25. Diffusive dye-forming couplers: page 65 lines 29 to 31,
26. Colored couplers: page 65 lines 32 to 38,
27. Functional coupler summary: page 65 lines 39 to 44,
28. Bleaching accelerator-releasing couplers: page 65 lines 45 to 48,
29. Development accelerator-releasing couplers: page 65 lines 49 to 53,
30. Other DIR couplers: page 65 line 54 to page 66 to line 4,
31. Method of dispersing couplers: page 66 lines 5 to 28,
32. Antiseptic and mildewproofing agents: page 66 lines 29 to 33,
33. Types of sensitive materials: page 66 lines 34 to 36,
34. Thickness of lightsensitive layer and swelling speed: page 66 line 40 to page 67 line 1,
35. Back layers: page 67 lines 3 to 8,
36. Development processing summary: page 67 lines 9 to 11,
37. Developers and developing agents: page 67 lines 12 to 30,
38. Developer additives: page 67 lines 31 to 44,
39. Reversal processing: page 67 lines 45 to 56,
40. Processing solution open ratio: page 67 line 57 to page 68 line 12,
41. Development time: page 68 lines 13 to 15,
42. Bleach-fix, bleaching and fixing: page 68 line 16 to page 69 line 31,
43. Automatic processor: page 69 lines 32 to 40,
44. Washing, rinse and stabilization: page 69 line 41 to page 70 line 18,
45. Processing solution replenishment and recycling:
page 70 lines 19 to 23,
46. Developing agent built-in sensitive material: page 70 lines 24 to 33,
47. Development processing temperature: page 70 lines 34 to 38, and
48. Application to film with lens: page 70 lines 39 to 41.